Funds are requested for a new rotating anode generator and optical system for a macromolecule crystallography X-ray data collection facility. The facility serves four Major Users and six Minor Users that are funded by NIH and have strong on-going programs and records of achievement. The current generator (purchased 1987) and optics (purchased 1997) are approaching obsolescence. Furthermore, contemporary systems offer considerably improved performance and will allow analysis of smaller, more weakly diffracting crystals, and crystals of larger complexes that have longer unit cell dimensions. [unreadable] [unreadable]